Understanding the Cardiac Benefits of Exercise at the Cellular and Molecular Level

项目总结/摘要 心力衰竭（HF）是发病率和死亡率不断增长的原因。尽管有最好的治疗方法， 许多HF患者的预后仍然很差，这强调了对新HF疗法的未满足的临床需求。 这一杰出研究者奖的申请灵感来自于观察，运动可以保护 心脏，促进心肌细胞（CM）存活和增殖，同时减少纤维化和炎症。然而 我们对这些负责任的机制知之甚少，也不知道它们是否可以用于治疗。在这里， 我计划利用NHLBI R35 Outstanding提供的长期支持和科学灵活性 研究者奖，以阐明运动对心脏有益的细胞和分子基础， 在临床前模型中验证潜在的新治疗靶点。我们发现，虽然运动和 病理性应激均诱导心肌肥厚，运动诱导心肌肥厚的机制 肥大在很大程度上是不同的，而不是导致不利的后遗症，矛盾的是保护心脏 (Cell，2010）。我们还发现，运动可以显著增强成年人的内源性心肌细胞生成， 哺乳动物心脏（Nature Comm.，2018年）。在某些情况下，模仿运动中看到的变化不仅 预防但可以逆转已建立的HF（Science transl.医学、2019年）。在这里，我们提出了一个广泛的计划， 为了描述运动的细胞和分子效应，确定介导运动的机制途径， 心肌形成和运动的其他益处，并探索这些途径的转化潜力 在临床前模型中。为了描述心肌细胞和非心肌细胞对运动的适应性反应， 心肌细胞，将采用一系列无偏见的发现工具，包括单核RNA- 测序（snRNA-seq）、批量RNA-seq和转座酶可降解染色质测定（ATAC-seq）。 snRNA-seq将提供对运动引起的细胞系特异性基因表达变化的洞察 随着时间的推移，这种方法将与谱系特异性功能获得和丧失模型相结合， 定义单元类型之间的串扰。将使用几种标记工具来帮助识别划分 在snRNA-seq研究中使用CM来描述这一动态过程，并测试特定的假设， CM亚群和/或容许环境是心肌发生所必需的。统计学 将使用相关的体外细胞筛选具有保护作用和心肌发生作用的强有力的候选物。 培养和体内斑马鱼模型。最有希望的将在临床前小鼠和猪中进行研究 模型，以发现新的生物途径和开发新的治疗方法。R35机制 独特地提供了所需的灵活性和时间框架，以支持所提出的无偏见的发现， 生物信息学分析和独特动物模型的产生。成功完成本计划 将促进我们对心肌形成和运动对心脏的有益影响的理解， 描绘具有减轻心力衰竭潜力的途径，从而满足迫切的临床需求。

Project Summary/Abstract Heart failure (HF) is a growing cause of morbidity and mortality. Despite the best available treatments, prognosis remains poor for many HF patients underscoring the unmet clinical need for new HF therapies. This Outstanding Investigator Award application is inspired by the observation that exercise protects the heart, promoting cardiomyocyte (CM) survival and proliferation while reducing fibrosis and inflammation. Yet we understand little of the responsible mechanisms and whether they can be exploited therapeutically. Here, I plan to leverage the longer-term support and scientific flexibility afforded by the NHLBI R35 Outstanding Investigator Award to illuminate the cellular and molecular basis of the cardiac benefits of exercise and to validate potential new therapeutic targets in preclinical models. We discovered that although exercise and pathological stress both induce cardiac hypertrophy, the mechanisms underlying exercise-induced hypertrophy are largely distinct and, rather than leading to adverse sequelae, paradoxically protect the heart (Cell, 2010). We also found that exercise dramatically enhances endogenous cardiomyogenesis in the adult mammalian heart (Nature Comm., 2018). In some cases, mimicking the changes seen in exercise not only prevents but can reverse established HF (Science Transl. Med., 2019). Here we propose a broad program to delineate the cellular and molecular effects of exercise, define the mechanistic pathways mediating cardiomyogenesis and other benefits of exercise, and explore the translational potential of these pathways in preclinical models. To describe the heart’s adaptive response to exercise in cardiomyocytes and non- cardiomyocytes, a range of unbiased discovery tools will be employed including single nucleus RNA- sequencing (snRNA-seq), bulk RNA-seq, and Assay for Transposase-Accessible Chromatin (ATAC-seq). snRNA-seq will provide insight into cell lineage-specific changes in gene expression in response to exercise over time, and this approach will be combined with lineage-specific gain- and loss-of-function models to help define crosstalk between cell types. Several labeling tools will be used to facilitate identification of dividing CMs in snRNA-seq studies to profile this dynamic process and test the hypotheses that specific subpopulations of CMs and/or permissive environments are required for cardiomyogenesis. Statistically robust candidates will be screened for protective and cardiomyogenic effects using relevant in vitro cell culture and in vivo zebrafish models. The most promising will be studied in preclinical murine and porcine models to uncover new biological pathways and develop new therapeutic approaches. The R35 mechanism uniquely provides the flexibility and timeframe required to support the proposed unbiased discovery and bioinformatic analyses and the generation of unique animal models. Successful completion of this program will advance our understanding of cardiomyogenesis and the beneficial effects of exercise in the heart, while delineating pathways with the potential to mitigate heart failure, thus meeting a pressing clinical need.